The present invention relates to rotary systems and equipment for high-speed processing of paper and card stock, and more particularly to systems and equipment designed to score (crease) and perforate such stock.
For many years, rotary devices have been used to cut, score and perforate paper and card stock in recognition of the considerably higher throughput rates afforded by such devices. In essence, the stock is fed between a processing (e.g. scoring) disc or roller and a counter-directionally rotated back-up disc or roller. The arrangement is particularly well-suited to process a continuous web of paper or card stock. U.S. Pat. No. 1,091,204 (Ferres) illustrates an early approach.
More recently, rigid processing tools have been used in combination with resilient opposing or back-up members, for example, as shown in U.S. Pat. No. 3,318,206 (Kuehn et al.) and U.S. Pat. No. 5,045,045 (Davenport et al.). Similarly, it is known to fabricate a resilient processing tool, for example the resilient compression rings shown in U.S. Pat. No. 3,977,310 (Keck). Each compression wheel, in the form of an O-ring, is seated in a groove formed into a rigid main body.
U.S. Pat. No. 6,572,519 (Harris) shows a creasing device in which creasing rings, more particularly rubber O-rings, are removably received in grooves formed into a rigid cylindrical male roller. A rigid female roller is provided with grooves corresponding to the O-ring locations. Harris advises that the male roller can have grooves of different widths to accommodate O-rings of different widths, and further that the grooves in the male roller can be formed to different depths to provide for O-rings that project from the roller at different heights.
While suitable for particular applications, this approach has limited flexibility. For example, if the narrowest or shallowest of the grooves is positioned near a given end of the male roller, and the operator needed to re-position the narrowest or farthest-projecting O-ring near the opposite end or along a medial region, another roller with a different arrangement of grooves would be needed.
Other disadvantages arise from the nature of the O-rings, which when suitable for scoring have extremely small diameters, e.g. in the range of 0.025 to 0.035 inches (0.63-0.88 mm). This renders the O-rings subject to excessive force concentrations that can lead to tearing, cracking or other damage when the rings are stretched to install them onto a male roller. Also, since the tensile force necessary to positively secure the O-rings on the roller is large in comparison to the O-ring cross-sectional area, the ring is susceptible to cold flow and relaxation of the tension, which over time diminish the tension and provide a less secure mounting of the ring.
Accordingly, the present invention has several aspects directed to one or more of the following objects:                to provide a resilient annular scoring tool configured to accommodate higher tensile forces for a more secure mounting around a grooved roller, with more stability in terms of maintaining the desired position of the radially outward or working end of the scoring tool;        to provide a resilient annular scoring tool that is less susceptible to wear and fatigue from repeated elongations during installation onto and removal from rigid grooved rollers;        to provide a roller assembly adapted to accommodate differences in size, shape, degree of radial protection and axial location of scoring blades while using a single grooved roller; and        to provide a paper processing roller assembly that accommodates different combinations of, and different axial spacings between, scoring tools, perforating tools and other processing tools in a single roller arrangement.        